How can I use ec2.py and localhost at the same time

Question

How can I use the ec2.py to get a dynamic list of ec2 hosts and also use localhost as a host. I have googled over and over and can't seem to find a good solution. I have come across some close answers but all seem to require breaking your tasks down into two separate playbooks that can't be run at the same time.

Answer 1

This isn't the only solution—valid suggestions have been made—but what I almost always end up doing when using the EC2 inventory plugin is exploiting an Ansible feature that I think many people don't know about: you can use a directory as inventory.

Ansible looks for executables and flat files in a directory and merges their results. This is very helpful because you can use a flat file to make nice aliases for dynamic groups, and add localhost in there, possibly setting some variables for it.

$ tree inventory/staging
inventory/staging
├── base
├── ec2.ini
├── ec2.py
└── group_vars -> ../group_vars

An excerpt of the file base looks like this:

[localhost]
# I need to tell Ansible which Python on my system has boto for AWS
127.0.0.1 ansible_python_interpreter=/usr/local/bin/python

# The EC2 plugin will populate these groups, but we need to add empty entries
# here to make aliases for them below.
[tag_Stage_staging]
[tag_Role_webserver]

[staging:children]
tag_Stage_staging

[webservers:children]
tag_Role_webserver

You then just point to the directory for inventory:

$ ansible -i inventory/staging webservers -m ec2_facts
# OR
$ export ANSIBLE_HOSTS=inventory/staging
$ ansible webservers -m ec2_facts

Answer 2

I was trying to solve a similar issue.

I had a bunch of hosts which accepted connections from the Ansible host. For security reasons the Ansible host was not allowed to connect to itself. However, I needed to run the Common play on all host.

I specified all hosts, excluded the Ansible host, and then added localhost:

- name: Common
  hosts: "tag_name_*:!tag_name_ansible:localhost"
  roles:
    - common

Adding localhost worked fine even when using the EC2 inventory script. I am using Ansible 1.7 with an up-to-date EC2 inventory script.

Answer 3

I think you can achieve what you want to do using the -l parameter of the ansible-playbook command.

We do something similar and the ansible-playbook command we use looks similar to this

ansible-playbook -l tag_foo_bar:localhost -U username -i ec2.py playbook.yml

The part after the -l is just an ansible pattern (http://docs.ansible.com/intro_patterns.html) which means "limit execution to all instances with tag 'foo=bar' AND the localhost host". The important part is the colon which just means "and".